The present invention relates to cellulose ester film, an optical film for optical use, a polarizing plate, an optical compensation film and a liquid crystal display, and particularly to an optical film such as a protective film of a polarizing plate, a phase difference film, or a viewing angle increasing film used in a liquid crystal display, various functional films such as an anti-reflective film used in a plasma display or various functional films used in an organic EL display.
Recently, a compact note type personal computer displaying a highly precise image has been developed. Synchronizing with the development, a protective film of a polarizing plate, which is thinner and has a higher performance, has been required. Cellulose ester is widely used as material of a protective film of a polarizing plate, in view of its transparency and refractive index. However, a simple thinning of the film produces various problems.
A cellulose ester film used in a protective film of a polarizing plate contains an ultraviolet absorber, in order to protect a polarizing element or a liquid crystal from ultraviolet light. Accordingly, a simple thinning of the film cannot sufficiently shield ultraviolet light, and therefore, the ultraviolet absorber amount contained in the film need be increased.
There is a proposal regarding an ultraviolet absorber in Japanese Patent O.P.I. Publication Nos. 6-130226 and 7-11056.
It has been found that the increased amount in the film of the ultraviolet absorber proposed in these patents produces problems in that the ultraviolet absorber is adhered to peeling rollers or transporting rollers during manufacture of the film, and produces troubles or lowers production efficiency.
There is proposed, in Japanese Patent O.P.I. Publication No. 8-148430, a protective film of a polarizing plate contains an ultraviolet absorbent polymer.
However, the ultraviolet absorbent polymer proposed in this patent has poor compatibility with cellulose ester. The increased amount of the polymer provides a high haze, and the polymer is not satisfactory in its application to a liquid crystal display requiring high precision
An optical compensation film is a film having optically anisotropy capable of being used in a liquid crystal display as an alternative of CRT.
A liquid crystal display has problems in viewing angle that displaying images quality lower when viewing obliquely, since it employs a liquid crystalline material having anisotropy, and its improvement has been desired.
Anisotropic materials, which are obtained by fixing orientation of a liquid crystalline compound, have been mainly used as an optical compensation film. They are ordinarily manufactured by coating a liquid crystalline compound-containing solution on a cellulose ester film. An ultraviolet absorber contained in the cellulose ester film has problems in that it bleeds out and contaminates the liquid crystalline compound, resulting in disorder of orientation of the liquid crystalline compound or haze of the film.
An object of the invention is to provide a cellulose ester film with few coating defects, excellent productivity, and excellent transparency, and to provide an optical film, a polarizing plate, an optical compensation film and a liquid crystal display each employing the film.
Another object of the invention is to provide an optical film having an excellent spectral absorption property, reduced bleed out, and an excellent weather-proof.
The above problems in the invention can be solved by the following constitutions:
1. A cellulose ester film comprising (a) an ultraviolet absorbent polymer having at least one of repeating units represented by the following formulae (1) and (2) and repeating units having ultraviolet absorbent structures represented by the following formulae (3), (4) and (5), (b) an ultraviolet absorbent polymer which is a copolymer of a repeating unit represented by the following formula (6), (7) or (19) with a monomer unit derived from another ethylenically unsaturated monomer, (c) an ultraviolet absorbent polymer which is a copolymer of a monomer represented by the following formula (8) with a monomer represented by the following formula (9), or (d) modified cellulose in which an ultraviolet absorbent structure bonds directly or through a spacer to a hydroxy group of cellulose or its derivative: 
wherein J1 represents xe2x80x94Oxe2x80x94, xe2x80x94NR1xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94POOxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94NR2COxe2x80x94, xe2x80x94NR3COOxe2x80x94, xe2x80x94NR4CONR5xe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94OCONR6xe2x80x94, xe2x80x94CONR7xe2x80x94, xe2x80x94NR8SOxe2x80x94, xe2x80x94NR9SO2xe2x80x94, xe2x80x94SONR10xe2x80x94, or xe2x80x94SO2NR11xe2x80x94, in which R1 through R11 independently represent a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; and Sp1 represents a divalent linkage which may have a halogen atom or a substituent, provided that an ultraviolet absorbent structure bonds directly or through a spacer to Sp1 or forms a part of the polymer main chain, 
wherein J2 and J3 represent the same group as J1 denoted in formula (1) above, and may be the same or different; Sp2 and Sp3 independently represent a divalent linkage which may have a halogen atom or a substituent, and may be the same or different, provided that an ultraviolet absorbent structure bonds directly or through a spacer to at least one of Sp2 and Sp3 or forms a part of the polymer main chain in at least one of Sp2 and Sp3, 
wherein R12 through R25 independently represent a hydrogen atom, a halogen atom or a substituent, provided that the two adjacent groups of R12 through R25 may combine with each other to form a ring, and provided that the ultraviolet absorbent structure of formula (3) bonds directly or through a spacer to the polymer main chain or forms a part of the polymer main chain, 
wherein R26 and R27 independently represent an alkyl group having a carbon atom number of 1 to 10; R28, R29 and R30 independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group or a substituted or unsubstituted amino group; X and Y independently represent an electron withdrawing group, provided that R26 through R30, X and Y may have a halogen atom or a substituent or may combine with another to form a 5- or 6-member ring, and provided that the ultraviolet absorbent structure of formula (4) bonds directly or through a spacer to the polymer main chain or forms a part of the polymer main chain, 
wherein R66 through R71 independently represent a hydrogen atom, a halogen atom or a substituent, provided that the two adjacent groups of R66 through R71 may combine with each other to form a ring; X and Y independently represent an electron withdrawing group, provided that X and Y may have a halogen atom or a substituent but do not combine with each other to form a ring; and provided that the ultraviolet absorbent structure of formula (5) bonds directly or through a spacer to the polymer main chain or forms a part of the polymer main chain, 
wherein R31 and R32 independently represent a halogen atom or a substituent; l represents 0, 1, 2, or 3, provided that when l is 2 or 3, plural R31s may be the same or different; m represents 0, 1, 2, 3, or 4, provided that when m is 2, 3 or 4, plural R32s may be the same or different; J4 represents a group selected from *xe2x80x94Oxe2x80x94, *xe2x80x94NR1xe2x80x94, *xe2x80x94Sxe2x80x94, *xe2x80x94SOxe2x80x94, *xe2x80x94SO2xe2x80x94, *xe2x80x94POOxe2x80x94, *xe2x80x94COxe2x80x94, *xe2x80x94COOxe2x80x94, *xe2x80x94NR2COxe2x80x94, *xe2x80x94NR3COOxe2x80x94, *xe2x80x94NR4CONR5xe2x80x94, *xe2x80x94OCOxe2x80x94, *xe2x80x94OCONR6xe2x80x94, *xe2x80x94CONR7xe2x80x94, *xe2x80x94NR8SOxe2x80x94, *xe2x80x94NR9SO2xe2x80x94, *xe2x80x94SONR10xe2x80x94, *xe2x80x94SO2NR11xe2x80x94 or *xe2x80x94OCOR12xe2x80x94, in which symbol xe2x80x9c*xe2x80x9d represents that the group bonds to the ultraviolet absorbent structure at the position xe2x80x9c*xe2x80x9d (on the side of J4 opposite Sp4) and R1 through R12 independently represent the same as R1 through R11 denoted in formula (1) above; and Sp4 represents a divalent linkage which may have a halogen atom or a substituent, 
wherein R33 and R34 independently represent a halogen atom or a substituent; o represents 0, 1, 2 or 3, provided that when o is 2 or 3, plural R34s may be the same or different; s represents 0, 1, 2, 3 or 4, provided that when s is 2, 3 or 4, plural R33s are the same or different; J5 represents a group selected from *xe2x80x94Oxe2x80x94, *xe2x80x94NR1xe2x80x94, *xe2x80x94Sxe2x80x94, *xe2x80x94SOxe2x80x94, *xe2x80x94SO2xe2x80x94, *xe2x80x94POOxe2x80x94, *xe2x80x94COxe2x80x94, *xe2x80x94COOxe2x80x94, *xe2x80x94NR2COxe2x80x94, *xe2x80x94NR3COOxe2x80x94, *xe2x80x94NR4CONR5xe2x80x94, *xe2x80x94OCOxe2x80x94, *xe2x80x94OCONR6xe2x80x94, *xe2x80x94CONR7xe2x80x94, *xe2x80x94NR8SOxe2x80x94, *xe2x80x94NR9SO2xe2x80x94, *xe2x80x94SONR10xe2x80x94, *xe2x80x94SO2NR11xe2x80x94 or *xe2x80x94OCOR12xe2x80x94, in which symbol xe2x80x9c*xe2x80x9d represents that the group bonds to the ultraviolet absorbent group at the position xe2x80x9c*xe2x80x9d (on the side of J5 opposite Sp5) and R1 through R12 independently represent the same as R1 through R11 denoted in formula (1) above; and Sp5 represents a divalent linkage which may have a halogen group or a substituent, 
wherein R35 through R36 independently represent a halogen atom or a substituent; r represents 0, 1, 2 or 3, provided that when r is 2 or 3, plural R36s are the same or different; q represents 0, 1, 2, 3 or 4, provided that when q is 2, 3 or 4, plural R35s may be the same or different; R37 through R39 independently represent a hydrogen atom, a halogen atom or a substituent; and Sp6 represents a divalent linkage which may have a halogen atom or a substituent, 
wherein R111 represents a halogen atom or a substituent positioned on the benzene ring through an oxygen atom, a nitrogen atom or a sulfur atom; R112 represents a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted heterocyclic group; a represents an integer of from 1 to 4, provided that plural R111s or plural R112s may be the same or different; R113, R115, and R116 independently represent a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted heterocyclic group; R114 represents a substituent positioned on the benzene ring through an oxygen atom or a nitrogen atom; and at least one of R111 through R116 has a group represented by the following formula (20), 
wherein L represents a divalent linkage or a simple bond; and R110 represents a hydrogen atom or a substituted or unsubstituted alkyl group.
2. The cellulose ester film of item 1 above, wherein the cellulose ester film has a transmittance at 380 nm of 0 to 10%.
3. The cellulose ester film of item 1 above, wherein the cellulose ester film has a haze of 0 to 0.5.
4. The cellulose ester film of item 1 above, wherein the ultraviolet absorbent polymer is a copolymer of the repeating unit represented by formula (1), (2), (6), (7) or (19) or a repeating unit having an ultraviolet absorbent structure represented by formula (3), (4) or (5) with another ethylenically unsaturated monomer.
5. The cellulose ester film of item 4 above, wherein the ethylenically unsaturated monomer is acrylic ester comprising a hydroxy group or an ether bond or methacrylic ester comprising a hydroxy group or an ether bond.
6. The cellulose ester film of item 1 above, wherein the ultraviolet absorbent polymer is the copolymer of a repeating unit represented by formula (6) and a monomer unit derived from another ethylenically unsaturated monomer, the content of the repeating unit represented by formula (6) in the copolymer being 1 to 45% by weight.
7. The cellulose ester film of item 6 above, wherein the ethylenically unsaturated monomer is acrylic ester comprising a hydroxy group or an ether bond or methacrylic ester comprising a hydroxy group or an ether bond.
8. The cellulose ester film of item 1 above, wherein the ultraviolet absorbent polymer is the copolymer of a repeating unit represented by formula (7) and a monomer unit derived from another ethylenically unsaturated monomer, the content of the repeating unit represented by formula (7) in the copolymer being 1 to 55% by weight.
9. The cellulose ester film of item 8 above, wherein the ethylenically unsaturated monomer is acrylic ester comprising a hydroxy group or an ether bond or methacrylic ester comprising a hydroxy group or an ether bond.
10. The cellulose ester film of item 1 above, wherein the ultraviolet absorbent polymer is the copolymer of a repeating unit represented by formula (19) and a monomer unit derived from another ethylenically unsaturated monomer, the content of the repeating unit represented by formula (19) in the copolymer being 1 to 55% by weight.
11. The cellulose ester film of item 1 above, wherein the ultraviolet absorbent polymer is the copolymer of a repeating unit represented by formula (7) and a monomer unit derived from another ethylenically unsaturated monomer, and wherein in formula (7), s and o are not simultaneously zero.
12. The cellulose ester film of item 11 abovel, wherein the content of the repeating unit represented by formula (7) in the copolymer is 1 to 55% by weight.
13. The cellulose ester film of item 1 above, wherein the cellulose ester of the cellulose ester film is a lower fatty acid ester of cellulose.
14. The cellulose ester film of item 1 above, wherein the compound having an ultraviolet structure represented by formula (3), (4), or (5), or the monomer, from which the repeating unit having an ultraviolet structure represented by formula (1), (2), (6), (7), or (19) is derived, has a molar extinction coefficient at 380 nm of not less than 4000.
15. The cellulose ester film of item 1 above, wherein the compound having an ultraviolet structure represented by formula (3), (4), or (5), or the monomer, from which the repeating unit having an ultraviolet structure represented by formula (1), (2), (6), (7), or (19) is derived, has a molar extinction coefficient at 380 nm of not less than 4000, and a ratio of molar extinction coefficient at 380 nm to molar extinction coefficient at 400 nm of not less than 20.
16. The cellulose ester film of item 1 above, wherein the ultraviolet absorbent polymer has a weight average molecular weight of 2,000 to 20,000.
17. The cellulose ester film of item 1 above, wherein the cellulose ester film is a member for constituting a liquid crystal display.
18. The cellulose ester film of item 17 above, wherein the cellulose ester film is a polarizing plate protective film.
19. The cellulose ester film of item 17 above, wherein the cellulose ester film is a support for an optical compensation film.
20. The cellulose ester film of item 1 above, wherein the thickness of the cellulose ester film is 5 to 200 xcexcm.
21. The cellulose ester film of item 20 above, wherein the thickness of the cellulose ester film is 20 to 65 xcexcm.
22. A polarizing plate comprising a first polarizing plate protective film, a polarizing element and a second polarizing plate protective film, wherein at least one of the first polarizing plate protective film or the second polarizing plate protective film is the cellulose ester film of item 1 above.
23. The polarizing plate of item 22 above, wherein the cellulose ester film comprises an ultraviolet absorbent polymer which is a copolymer of a repeating unit represented by formula (7) and a monomer unit derived from another ethylenically unsaturated monomer, the content of the repeating unit represented by formula (7) in the copolymer being 1 to 55 weight %.
24. A liquid crystal display comprising a first polarizing plate, a second polarizing plate, and a liquid crystal cell provided between the first and second polarizing plates, the first polarizing plate being arranged on the viewer side of the display, wherein the first polarizing plate has a first film, a second film and a first polarizing film between the first and second films so that the second film is provided on the first polarizing film on the liquid crystal cell side, the second polarizing plate has a third film, a fourth film and a second polarizing film between the third and fourth films so that the third film is provided on the second polarizing film on the liquid crystal cell side, and at least one of the first, second, third and fourth films is the cellulose ester film of item 1 above.
25. The liquid crystal display of item 24 above, wherein the cellulose ester film comprises an ultraviolet absorbent polymer which is a copolymer of a repeating unit represented by formula (7) and a monomer unit derived from another ethylenically unsaturated monomer, the content of the repeating unit represented by formula (7) in the copolymer being 1 to 55 weight %.
101. A cellulose ester film containing an ultraviolet absorbent polymer, wherein the film has a transmittance at 380 nm of 0 to 10%, and a haze of 0 to 0.5.
102. A cellulose ester film comprising an ultraviolet absorbent polymer comprising a repeating unit represented by formula (1) above.
103. A cellulose ester film comprising an ultraviolet absorbent polymer comprising a repeating unit represented by formula (2) above.
104. A cellulose ester film comprising an ultraviolet absorbent polymer comprising a repeating unit having an ultraviolet absorbent structure represented by formula (3) above.
105. A cellulose ester film comprising an ultraviolet absorbent polymer comprising a repeating unit having an ultraviolet absorbent structure represented by formula (4) above.
106. A cellulose ester film comprising an ultraviolet absorbent polymer comprising a repeating unit having an ultraviolet absorbent structure represented by formula (5) above.
107. A cellulose ester film comprising an ultraviolet absorbent polymer comprising a repeating unit represented by formula (6) above.
108. A cellulose ester film containing an ultraviolet absorbent polymer comprising a repeating unit represented by formula (7) above.
109. A cellulose ester film containing a copolymer of a first monomer represented by formula (8) above and a second monomer represented by formula (9) above.
110. A cellulose ester film comprising modified cellulose in which an ultraviolet absorbent group bonds directly or through a spacer to a hydroxy group of cellulose or its derivative.
111. The cellulose ester film of any one of items 102 to 110, having a haze of 0 to 0.5.
112. The cellulose ester film of any one of items 102 to 111, having a transmittance at 380 nm of 0 to 10%.
113. An optical film comprised of the cellulose ester film of any one of items 101 to 112.
114. An optical film of item 113, wherein the cellulose ester is a lower fatty acid ester of cellulose.
115. A polarizing plate comprising a first optical film, a polarizing element and a second optical film, wherein the first optical film or the second optical film is the optical film of item 113 or 114.
116. A liquid crystal display employing the polarizing plate of item 115.
117. An optical compensation film employing as a support the cellulose ester film of any one of items 101 to 112.
118. The optical compensation film of item 117, wherein a discotic compound is contained in an optically anisotropic layer.
119. The optical compensation film of item 117, wherein a biaxial liquid crystal compound contained in an optically anisotropic layer.
120. The optical compensation film of item 117, wherein a rod-shaped liquid crystal compound is contained in an optically anisotropic layer.
201. An optical film comprising a copolymer of an ultraviolet absorbent monomer with a molar extinction coefficient at 380 nm of not less than 4000 with another ethylenically unsaturated monomer, wherein the copolymer has a weight average molecular weight of 2,000 to 20,000.
202. An optical film comprising a copolymer of an ultraviolet absorbent monomer with a molar extinction coefficient at 380 nm of not less than 4000 with another ethylenically unsaturated monomer and a ratio of molar extinction coefficient at 400 nm to molar extinction coefficient at 380 nm being not less than 20, wherein the copolymer has a weight average molecular weight of 2,000 to 20,000.
203. The optical film of item 201 or 202, wherein the ultraviolet absorbent monomer content of the copolymer is 20 to 70 weight %.
204. The optical film of any one of items 201 through 203, wherein the ultraviolet absorbent monomer is a benzotriazole type ultraviolet absorber.
205. The optical film of any one of items 201 through 204, wherein the ultraviolet absorbent monomer is a compound represented by formula (19) above.
206. The optical film of any one of items 201 through 205, wherein the ethylenically unsaturated monomer is methacrylate or acrylate each having a hydroxy group or an ether bond.
207. The optical film of any one of items 201 through 206, comprising silicon dioxide particles having an average primary order particle size of 3 to 20 nm, and an apparent gravity of 70 to 300 g/liter.
208. The optical film of any one of items 201 through 207, being a cellulose ester film.
209. The optical film of item 208, wherein the cellulose ester film is cellulose acetate propionate.
210. The optical film of any one of items 201 through 209, having a thickness of 20 to 65 xcexcm.
211. A method of manufacturing a cellulose ester film comprising the steps of:
providing a dope containing cellulose ester and a solution containing an ultraviolet absorber;
mixing the dope with the solution in a in-line mixer to obtain a mixture solution; and
stirring the mixture solution.
212. A polarizing plate comprising a first optical film, a polarizing element and a second optical film, wherein the first optical film or the second optical film is the optical film of any one of items 201 through 210.
213. A display comprising a polarizing plate, employing the polarizing plate of item 212 above.
The present inventors have made an extensive study in order to solve the above problems occurring due to a low molecular weight ultraviolet absorbent, and as a result, they have developed an ultraviolet absorbent polymer having excellent compatibility that prevents property lowering or roller contamination due to bleed out phenomenon, does not produce lowering of an optical property or orientation disorder of an optical compensation film, and results in cost decrease. Further, the ultraviolet absorbent polymer provides excellent heat and humidity resistant properties under high humidity and high temperature condition, as well as prevention of bleed out.
Next, the present invention will be explained in detail.
The ultraviolet absorbent polymer of the invention of item 2 or 3 may be any as long as it comprises a repeating unit represented by formula (1) or (2).
In formula (1), J1 represents xe2x80x94Oxe2x80x94, xe2x80x94NR1xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94POOxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94NR2COxe2x80x94, xe2x80x94NR3COOxe2x80x94, xe2x80x94NR4CONR5xe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94OCONR6xe2x80x94, xe2x80x94CONR7xe2x80x94, xe2x80x94NR8SOxe2x80x94, xe2x80x94NR9SO2xe2x80x94, xe2x80x94SONR10xe2x80x94, or xe2x80x94SO2NR11xe2x80x94, and preferably xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94NR2COxe2x80x94, or xe2x80x94CONR7xe2x80x94, in which R1 through R11 independently represent a hydrogen atom, an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a hydroxyethyl group, a methoxymethyl group, a trifluoromethyl group, or a t-butyl group), or an aryl group (for example, a phenyl group, a naphthyl group, a p-tolyl group or a p-chlorophenyl group). The alkyl group or the aryl group described above may be substituted or unsubstituted.
Sp1 represents a divalent linkage, and is not specifically limited. Sp1 is preferably a divalent linkage comprising an alkylene group or an arylene group, and more preferably an alkylene group having a carbon atom number of 1 to 10 or an arylene group having a carbon atom number of 4 to 10. The divalent linkage may have a halogen atom or a substituent. Examples of the substituent include an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a hydroxyethyl group, a methoxymethyl group, a trifluoromethyl group, or a t-butyl group), an aryl group (for example, a phenyl group, a naphthyl group, a p-tolyl group or a p-chlorophenyl group), an acyl group (for example, an acetyl group, a propanoyl group or a butyloyl group), a sulfonyl group (for example, a methanesulfonyl group, an ethanesulfonyl group or a phenylsulfonyl group), an alkoxy group (for example, a methoxy group, an ethoxy group, an isopropoxy group or an n-butoxy group), an aryloxy group (for example, a phenoxy group), an alkyltio group (for example, a methylthio group, an ethylthio group or an n-butylthio group), an arylthio group (for example, a phenylthio group), an amino group, an alkylamino group (for example, a methylamino group, an ethylamino group or dimethylamino group), an arylamino group (for example, a phenylamino group), an acylamino group (for example, a acetylamino group or a propionylamino group), a hydroxy group, a cyano group, a carbamoyl group (for example, a methylcarbamoyl group, an ethylcarbamoyl group or dimethylcarbamoyl group), a sulfamoyl group (for example, an ethylsulfamoyl group or dimethylsulfamoyl group), a sulfonamido group, an acyloxy group, an oxycarbonyl group, a sulfonylamino group (for example, a methanesulfonylamino group or a benzenesulfonylamino group), a ureido group (for example, a 3,3-dimethylureido group, a 1,3-dimethylureido group), a sulfamoylamino group (for example, dimethylsulfamoylamino group), an alkoxycarbonyl group (for example, a methoxycarbonyl group or an ethoxycarbonyl group), an aryloxycarbonyl group (for example, a phenoxycarbonyl group), a nitro group, an imido group (for example, a phthalimido group), and a heterocyclic group (for example, a pyridyl group, a benzimidazolyl group, a benzothiazolyl group or a benzoxazolyl group). The substituents are preferably a hydrogen atom, a halogen atom, an alkyl group, an acylamino group, a carbamoyl group, an acyloxy group or an oxycarbonyl group.
An ultraviolet absorbent group bonds directly or through a spacer to Sp1 or a part or all of an ultraviolet absorbent group forms a part of Sp1 in the polymer main chain.
The spacer herein referred to may be any divalent linkage group. The spacer is preferably a divalent linkage group comprising a substituted or unsubstituted alkylene group or a substituted or unsubstituted arylene group, or xe2x80x94Oxe2x80x94, xe2x80x94NR40xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94POOxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94NR41COxe2x80x94, xe2x80x94NR42COOxe2x80x94, xe2x80x94NR43CONR44xe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94OCONR45xe2x80x94 or xe2x80x94CONR46xe2x80x94, and more preferably is a combination of xe2x80x94Oxe2x80x94, xe2x80x94NR40xe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2, xe2x80x94POOxe2x80x94, xe2x80x94COxe2x80x94, xe2x80x94COOxe2x80x94, xe2x80x94NR41COxe2x80x94, xe2x80x94NR42COOxe2x80x94, xe2x80x94NR43CONR44xe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94OCONR45xe2x80x94 or xe2x80x94CONR46xe2x80x94 and a substituted or unsubstituted alkylene group or a substituted or unsubstituted arylene group.
R40 through R46 independently represent a hydrogen atom, a hydroxy group, an alkyl group, or an aryl group. The alkyl group or aryl group may have plural substituents. Examples of the substituents are the same as the substituents denoted in Sp1 above of formula (1).
The ultraviolet absorbent group in the invention may be any as long as the compound having it provides an extremely high absorption at 380 nm and does not substantially absorb a visible light of not shorter than 420 nm. Examples of the ultraviolet absorbent group include groups, in which one or more hydrogen atoms are abstracted from the following compounds (10) through (18). 
The ultraviolet absorbent group derived from formulae (10) through (18) may have one or more halogen atoms or substituents. Examples of the substituent include the same as the substituents denoted in Sp1 above of formula (1). The repeating unit represented by formula (1) or (2) may have the ultraviolet absorbent structure represented by formula (3), (4), (5) or (19) or the ultraviolet absorbent structure (corresponding to formula (11)) in the repeating unit represented by formula (6) or (7).
In formulae (10) through (18), R55 through R65 independently represent a hydrogen atom, a halogen atom or a substituent. Examples of the substituent are the same as the substituents denoted in Sp1 above of formula (1). It is preferred that in formula (12) R55 and R56 independently represent a hydrogen atom or an alkyl group, in formula (15) R57, R58 and R59 independently represent a hydrogen atom, an alkyl group or an aryl group and in formula (17) R60 and R61 represent an alkyl group.
It is preferred that in formulae (17) and (18) R62 through R65 independently represent an alkyl group, an aryl group, an alkoxy group, an alkylthio group or an amino group. In formula (15) X represents a methylene group or a chalcogen atom, preferably a sulfur atom.
In formulae (17) and (18), EWG1 through EWG4 each represent an electron attractive group. Examples of the electron attractive group include an acylamino group (for example, a acetylamino group or a propionylamino group), a sulfonylamino group (for example, a methanesulfonylamino group or a benzenesulfonylamino group), a sulfamoylamino group (for example, dimethylsulfamoylamino group), a carbamoyl group (for example, a methylcarbamoyl group, an ethylcarbamoyl group or dimethylcarbamoyl group), a sulfamoyl group (for example, an ethylsulfamoyl group or dimethylsulfamoyl group), an alkoxycarbonyl group (for example, a methoxycarbonyl group or an ethoxycarbonyl group), an aryloxycarbonyl group (for example, a phenoxycarbonyl group), a sulfonyl group (for example, a methanesulfonyl group, a butanesulfonyl group or a phenylsulfonyl group), an acyl group (for example, an acetyl group, a propanoyl group or a butyloyl group), a nitro group, a cyano group and a halogen atom. The preferred substituent is a cyano group, an acyl group, a sulfonyl group, an alkoxycarbonyl group or a carbamoyl group.
EWG1 and EWG2 in formula (17) need not be simultaneously electron attractive groups, and either one may be an electron attractive group, and EWG3 and EWG4 in formula (18) need not be simultaneously electron attractive groups, and either one may be an electron attractive group. R60 through R64, EWG1 and EWG2 in formula (17) may combine with another to form a 5- or 6-member ring, and R65, EWG3 and EWG4 in formula (18) may combine with another to form a 5- or 6-member ring.
In formula (2), J2 and J3 represent the same group as J1 denoted in formula (1) above, and may be the same or different. Sp2 and Sp3 represent a divalent linkage group, which may have a halogen atom or a substituent, and may be the same or different, provided that the ultraviolet absorbent group bonds directly or through a spacer to at least one of Sp2 and Sp3 or a part or total of the ultraviolet absorbent group form in at least one of Sp2 and Sp3 a part of the polymer main chain. Examples of the divalent linkage group represented by Sp2 and Sp3 or its substituent include the same as those denoted in Sp1 above.
Examples of the ultraviolet absorbent group include the same as those denoted in formula (1) above.
Another ultraviolet absorbent polymer of the invention may be any ultraviolet absorbent polymer comprising a repeating unit having an ultraviolet absorbent structure represented by formula (3), (4) or (5).
In formula (3), R12 through R25 independently represent a hydrogen atom, a halogen atom or a substituent, provided that the adjacent two of R12 through R25 may combine with each other to form a ring. Examples of the substituent include the same as those denoted in Sp1 above of formula (1). Further, the ultraviolet absorbent structure represented by formula (3) bonds directly or through a spacer to the polymer main chain or a part or total of the ultraviolet absorbent group form a part of the polymer main chain. Examples of the spacer include the same as those denoted in formula (1) above.
In formula (4), R26 and R27 independently represent an alkyl group having a carbon atom number of 1 to 10; R28, R29 and R30 independently represent an alkyl group, an alkoxy group, an alkylthio group or an amino group; and X and Y independently represent an electron attractive group, provided that R26 through R30, X and Y may have a halogen atom or a substituent. Examples of the electron attractive group include those denoted in EWG1 through EWG4 above, and examples of the substituent include the same as those denoted in Sp1 of formula (1) above. The above alkyl group, alkoxy group, alkylthio group or amino group may be substituted or unsubstituted.
R26 through R30, X and Y may combine with another to form a 5- or 6-member ring. Further, the ultraviolet absorbent structure represented by formula (4) bonds directly or through a spacer to the polymer main chain or a part or total of the ultraviolet absorbent group form a part of the polymer main chain. Examples of the spacer include the same as those denoted in formula (1) above.
In formula (5), R66 through R71 independently represent a hydrogen atom, a halogen atom or a substituent, provided that R66 through R70 may combine with another to form a ring. Preferably R66 through R70 independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an amino group or an alkylamino group, and R71 represents a hydrogen atom, a halogen atom or an alkyl group. X and Y independently represent the same as X and Y denoted in formula (4) above, respectively. Further, the ultraviolet absorbent structure represented by formula (5) bonds directly or through a spacer to the polymer main chain or a part or total of the ultraviolet absorbent group form a part of the polymer main chain. Examples of the spacer include the same as those denoted in formula (1) above. The two adjacent groups of R66 through R71 may combine with each other to form a ring, but X and Y do not combine with each other and do not form a ring.
Another ultraviolet absorbent polymer of the invention may be any ultraviolet absorbent polymer comprising a repeating unit represented by formula (6) or (7), which is a copolymer of a repeating unit represented by formula (6) or (7) and another ethylenically unsaturated monomer unit.
In formula (6) or (7), R31 through R34 independently represent a halogen atom or a substituent. Examples of the substituent include the same as those denoted in Sp1 of formula (1). l represents 0, 1, 2, or 3; m represents 0, 1, 2, 3, or 4; s represents 0, 1, 2, 3 or 4; o represents 0, 1, 2 or 3; J4 represents a group selected from *xe2x80x94Oxe2x80x94, *xe2x80x94NR1xe2x80x94, *xe2x80x94Sxe2x80x94, *xe2x80x94SOxe2x80x94, *xe2x80x94SO2xe2x80x94, *xe2x80x94POOxe2x80x94, *xe2x80x94COxe2x80x94, *xe2x80x94COOxe2x80x94, *xe2x80x94NR2COxe2x80x94, *xe2x80x94NR3COOxe2x80x94, *xe2x80x94NR4CONR5xe2x80x94, *xe2x80x94OCOxe2x80x94, *xe2x80x94OCONR6xe2x80x94, *xe2x80x94CONR7xe2x80x94, *xe2x80x94NR8SOxe2x80x94, *xe2x80x94NR9SO2xe2x80x94, *xe2x80x94SONR10xe2x80x94, or *xe2x80x94SO2NR11xe2x80x94, in which symbol xe2x80x9c*xe2x80x9d represents that the group bonds to the ultraviolet absorbent group at the position xe2x80x9c*xe2x80x9d (at the side of J4 opposite to Sp4), and preferably represents *xe2x80x94Oxe2x80x94, *xe2x80x94NR1xe2x80x94, *xe2x80x94Sxe2x80x94, *xe2x80x94SOxe2x80x94, *xe2x80x94SO2xe2x80x94, *xe2x80x94NR3COOxe2x80x94 or *xe2x80x94NR4CONR5xe2x80x94. J5 represents a group selected from *xe2x80x94Oxe2x80x94, *xe2x80x94NR1xe2x80x94, *xe2x80x94Sxe2x80x94, *xe2x80x94SOxe2x80x94, *xe2x80x94SO2xe2x80x94, *xe2x80x94POOxe2x80x94, *xe2x80x94COxe2x80x94, *xe2x80x94COOxe2x80x94, *xe2x80x94NR2COxe2x80x94, *xe2x80x94NR3COOxe2x80x94, *xe2x80x94NR4CONR5xe2x80x94, *xe2x80x94OCOxe2x80x94, *xe2x80x94OCONR6xe2x80x94, *xe2x80x94CONR7xe2x80x94, *xe2x80x94NR8SOxe2x80x94, *xe2x80x94NR9SO2xe2x80x94, *xe2x80x94SONR10xe2x80x94, or *xe2x80x94SO2NR11xe2x80x94, in which symbol xe2x80x9c*xe2x80x9d represents that the group bonds to the ultraviolet absorbent group at the position xe2x80x9c*xe2x80x9d (at the side of J5 opposite to Sp5), and preferably represents *xe2x80x94Oxe2x80x94, *xe2x80x94NR1xe2x80x94, *xe2x80x94Sxe2x80x94, *xe2x80x94SOxe2x80x94, *xe2x80x94SO2xe2x80x94, *xe2x80x94NR3COOxe2x80x94 or *xe2x80x94NR4CONR5xe2x80x94. R1 through R11 represent the same as R1 through R11 denoted in formula (1) above; and Sp4 or Sp5 represents a divalent linkage group which may have a halogen atom or a substituent, and examples of the linkage group or the substituent are the same as those denoted in Sp1 of formula (1) above. When l is 2 or 3, plural R31s may be the same or different, and when m is 2, 3, or 4, plural R32s may be the same or different. When o is 2 or 3, plural R34s may be the same or different, and when s is 2, 3, or 4, plural R33s may be the same or different. It is preferred that in formula (6), l and m are not simultaneously 0, and in formula (7), s and o are not simultaneously 0. In formula (7), Sp5 is preferably xe2x80x94C(xe2x95x90O)xe2x80x94Oxe2x80x94Sp5xe2x80x2, in which Sp5xe2x80x2 is the same as Sp5, and Sp5xe2x80x2 bonds with J5.
Next, an ultraviolet absorbent polymer having an ultraviolet structure represented by formula (19) will be explained below.
In formula (19), the substituent represented by R111 through R116 may have a further substituent, unless otherwise specifically specified. Any one of R111 through R116 is a group comprising a polymerizable group represented by formula (20). In formula (20), L represents a divalent linkage or a single bond, and R110 represents a hydrogen atom or a substituted or unsubstituted alkyl group. R110 is preferably a hydrogen atom or an alkyl group having a carbon atom number of 1 to 4. The group comprising a polymerizable group represented by formula (20) may be any of a group represented by R111 through R116, but is preferably R111, R113, R114 or R115, and more preferably R114.
R111 represents a halogen atom or a substituent positioned on the benzene ring through an oxygen atom, a nitrogen atom or a sulfur atom. xe2x80x9caxe2x80x9d represents an integer of from 1 to 4. R112 represents a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted heterocyclic group. When R111 or R112 is plural, plural R111s or plural R112s may be the same or different. R113 R115 and R116 independently represent a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted heterocyclic group. R114 represents a substituent positioned on the benzene ring through an oxygen atom or a nitrogen atom.
R111 represents a halogen atom or a substituent positioned on the benzene ring through an oxygen atom, a nitrogen atom or a sulfur atom. The halogen atom is fluorine, chlorine, or bromine, and preferably chlorine.
Examples of the substituent positioned on the benzene ring through an oxygen atom include a hydroxy group, an alkoxy group (for example, a methoxy group, an ethoxy group, a t-butoxy group or a 2-ethoxyethoxy group), an aryloxy group (for example, a phenoxy group, a 2,4-di-t-amylphenoxy group or a 4-(4-hydroxyphenylsulfonyl)phenoxy group), a heterocyclicoxy group (for example, 4-pyridyloxy, or 2-hexahydropyranyloxy), a carbonyloxy group (for example, alkylcarbonyloxy such as acetyloxy, trifluoroacetyloxy, or pyvaloyloxy, or arylcarbonyloxy such as benzoyloxy, pentafluorobenzoyloxy), a urethan group (for example, alkylurethan such as N,N-dimethylurethan, or arylurethan such as N-phenylurethan or N-(p-cyanophenyl)urethan), and a sulfonyloxy group (for example, alkylsulfonyloxy such as methanesulfonyloxy, trifluoremethanesulfonyloxy or n-dodecanesulfonyloxy, arylsulfonyloxy such as benzenesulfonyloxy, or toluenesulfonyloxy), and the substituent is preferably an alkoxy group having a carbon atom number of 1 to 6, and preferably 2 to 4.
Examples of the substituent positioned on the benzene ring through a nitrogen atom include a nitro group, an amino group (for example, an alkylamino group such as dimethylamino, cyclohexylamino, or n-dodecylamino or an arylamino group such as anilino or p-t-octylanilino), a sulfonylamino group (for example, an alkylsulfonylamino group such as methanesulfonylamino, heptafluoropropanesulfonylamino or hexadecylsulfonylamino, or an arylamino group such as p-toluenesulfonylamino or pentafluorobenzenesulfonylamino), a sulfamoylamino group (for example, an alkylsulfamoylamino such as N,N-dimethylsulfamoylamino or an arylsulfamoylamino group such as N-phenylsulfamoylamino), an acylamino group (for example, an alkylcarbonyl group such as acetylamino or myristoylamino or an arylcarbonyl group such as benzoylamino), and a ureido group (for example, an alkylureido group such as N,N-dimethylaminoureido or an arylureido group such as N-phenylureido or N-(p-cyanophenyl)ureido), and the substituent is preferably an acylamino group.
Examples of the substituent positioned on the benzene ring through a sulfur atom include an alkylthio group (for example, methylthio, t-octylthio), an arylthio group (for example, phenylthio), a heterocyclicthio (for example, 1-phenyltetrazole-5-thio or 5-methyl-1,3,4-oxadiazole-2-thio), a sulfinyl group (for example, alkylsulfinyl such as methanesulfinyl or trifluoromethanesulfinyl or arylsulfinyl such as p-toluenesulfinyl), a sulfonyl group (for example, alkylsulfonyl such as methanesulfonyl or trifluoromethanesulfonyl or arylsulfonyl such as p-toluenesulfonyl), and a sulfamoyl group (for example, alkylsulfamoyl such as dimethylsulfamoyl or 4-(2,4-di-t-amylphenoxy)butylaminosulfamoyl or arylsulfamoyl such as phenylsulfamoyl), and is preferably a sulfinyl group, and more preferably a sulfinyl group having a carbon atom number of 4 to 12.
xe2x80x9caxe2x80x9d represents an integer of 1 to 4, and is preferably 1 or 2. When a is 2 or more, plural R111s may be the same or different. The substitution position on the benzene ring of R111 is not limited, but R111 is positioned at preferably 4 or 5 position of the benzene ring.
R112 represents a hydrogen atom, an aliphatic group (for example, alkyl, alkenyl, or alkinyl), an aryl group (for example, phenyl or p-chlorophenyl), or a heterocyclic group (for example, 2-tetrafurfuryl, 2-thiophenyl, 4-imidazolyl, indoline-1-yl or 2-pyridyl). R112 is preferably a hydrogen atom or an alkyl group.
R113 represents a hydrogen atom, an aliphatic group, an aryl group or a heterocyclic group. R113 is preferably a hydrogen atom or an alkyl group having a carbon atom number of 1 to 12. R113 is especially preferably a branched alkyl group such as i-propyl, t-butyl, or t-amyl, since it provides an excellent durability.
R114 represents a substituent positioned on the benzene ring through an oxygen atom or a nitrogen atom, and examples of R114 include the same group as those denoted in the substituent positioned on the benzene ring through an oxygen atom or a nitrogen atom of R111. R114 is preferably an acylamino group or an alkoxy group. When R114 has a group represented by formula (20), it is preferred that R114 has a group represented by the following formula (21). It is also preferred that R114 has a group represented by the following formula (22). When R114 has a group represented by formula (22), the structure represented by formula (19) does not need to have a group represented by formula (20). 
wherein L2 represents an alkylene group having a carbon atom number of 1 to 12, and preferably a straight chained alkylene group having a carbon atom number of 3 to 6, R110 represents a hydrogen atom or a methyl group, and R200 represents an alkyl group having a carbon atom number of 1 to 12, and preferably 2 to 6.
R115 represents a hydrogen atom, an aliphatic group, an aryl group or a heterocyclic group. R115 is preferably a hydrogen atom or an alkyl group having a carbon atom number of 1 to 12, and especially preferably a branched alkyl group such as i-propyl, t-butyl, or t-amyl.
R116 represents a hydrogen atom, an aliphatic group, an aryl group or a heterocyclic group . R116 is preferably a hydrogen atom.
Preferred ultraviolet absorbing monomers used in the invention will be exemplified, below, but the invention is not limited thereto. 
Further another ultraviolet absorbent polymer of the invention may be any ultraviolet absorbent polymer comprising a copolymer of a first monomer represented by formula (8) and a second monomer represented by formula (9).
In formula (8) or formula (9), R35 and R36 independently represent a halogen atom or a substituent. Examples of the substituent include the same as those denoted in Sp1 of formula (1) above. r represents 0, 1, 2 or 3, and q represents 0, 1, 2, 3 or 4. When r is 2 or 3, plural R36s may be the same or different, and when q is 2, 3 or 4, plural R35s may be the same or different. R37 through R39 independently represent a hydrogen atom, a halogen atom or a substituent. Sp6 represents a divalent linkage group which may have a halogen atom or a substituent, and examples of the linkage group or the substituent are the same as those denoted in Sp1 of formula (1) above.
Still further another ultraviolet absorbent polymer of the invention may be any modified cellulose in which an ultraviolet absorbent group bonds directly or through a spacer to a hydroxy group of cellulose or its derivative. The modified cellulose in which an ultraviolet absorbent group bonds directly or through a spacer to a hydroxy group of cellulose or its derivative is a cellulose in which an ultraviolet absorbent group bonds directly or through a spacer to any one of the three hydroxy group contained in the repeating unit of cellulose. Examples of the ultraviolet absorbent group include the same as those denoted in Sp1 of formula (1) above, and examples of the spacer are the same as those denoted in Sp1 of formula (1) above. This ultraviolet absorbent polymer has an excellent compatibility with cellulose and does not produce bleeding out or crystal precipitation which has been problems during manufacture of a cellulose film or during saponification of the film with an alkali solution, since the repeating unit is a cellulose derivative. The repeating unit represented by formula (1) or (2), the ultraviolet absorbent structure represented by formula (3), (4), (5) or (19), or the ultraviolet absorbent structure (corresponding to formula (11)) in the repeating unit represented by formula (6) or (7) may bond directly or through a spacer to a hydroxy group of cellulose or its derivative.
The compound having an ultraviolet structure represented by formula (3), (4), (5), or the monomer, from which the repeating unit having an ultraviolet structure represented by formula (1), (2), (6), (7) or (19) is derived, preferably has a molar extinction coefficient at 380 nm of not less than 4000, and more preferably has a ratio of molar extinction coefficient at 380 nm to molar extinction coefficient at 400 nm of not less than 20.
The ultraviolet absorbent polymer in the invention comprises at least one of a polymer having a repeating unit represented by formula (1), (2), (6) or (7), a polymer comprising a repeating unit having an ultraviolet absorbent structure represented by formula (3), (4), (5) or (19), a copolymer of a monomer represented by formula (8) and a monomer represented by formula (9), and a modified cellulose in which an ultraviolet absorbent structure bonds directly or through a spacer to a hydroxy group of cellulose or its derivative. The ultraviolet absorbent polymer in the invention may be any homopolymer or any copolymer with another unit, as long as it comprises the repeating unit in the invention or the copolymer derived from the monomers in the invention.
Examples of the another monomer unit include a monomer unit comprising an acrylamide derivative, a monomer comprising an acrylate derivative, a monomer comprising a methacrylate derivative, a monomer comprising a vinyl ether derivative, a monomer comprising an ethylene oxide derivative, a monomer comprising a vinyl ester derivative, a monomer comprising a dicarboxylic acid derivative, a monomer comprising a diol derivative, and a monomer comprising a diamine derivative. When the ultraviolet absorbent polymer or modified cellulose in the invention is a copolymer, it is preferably a copolymer comprising an ethylenically unsaturated monomer unit. The ethylenically unsaturated monomer is especially preferably a methacrylate comprising a hydroxy group or an ether bond or an acrylate comprising a hydroxy group or an ether bond. Preferred examples of the ethylenically unsaturated monomer include methacrylic acid, methacrylate (for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, dimethylaminoethyl methacrylate, or diethylaminoethyl methacrylate), acrylic acid, acrylate (for example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, i-butyl acrylate, t-butyl acrylate, octyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethoxyethyl acrylate, acrylic acid diethylene glycol ethoxylate, 3-methoxybutyl acrylate, benzyl acrylate, dimethylaminoethyl acrylate or diethylaminoethyl acrylate), alkyl vinyl ether (for example, methyl vinyl ether, ethyl vinyl ether or butyl vinyl ether), vinyl ester (for example, vinyl formate, vinyl acetate, vinyl butyrate , vinyl caproate or vinyl stearate), acrylonitrile, vinyl chloride, and styrene. Of these monomers, the preferred monomer is a methacrylate comprising a hydroxy group or an ether bond (for example, hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate), or an acrylate comprising a hydroxy group or an ether bond (for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethoxyethyl acrylate, acrylic acid diethylene glycol ethoxylate or 3-methoxybutyl acrylate). One or more kinds of the monomer can be copolymerised with an ultraviolet absorbent monomer. The ultraviolet absorbent monomer content in the ultraviolet absorbent polymer is preferably 1 to 70% by weight, more preferably 20 to 70% by weight, and most preferably 30 to 60% by weight. Particularly when the ultraviolet absorbent polymer is a copolymer of a monomer unit represented by formula (6) and another ethylenically unsaturated monomer, the content of the monomer unit represented by formula (6) is preferably 1 to 45% by weight, more preferably 10 to 45% by weight, and most preferably 20 to 40% by weight. Particularly when the ultraviolet absorbent polymer is a copolymer of a monomer unit represented by formula (7) and another ethylenically unsaturated monomer, the content of the monomer unit represented by formula (7) is preferably 1 to 55% by weight, more preferably 10 to 55% by weight, and most preferably 20 to 50% by weight. Particularly when the ultraviolet absorbent polymer is a copolymer of a monomer unit represented by formula (19) and another ethylenically unsaturated monomer, the content of the monomer unit represented by formula (19) is preferably 1 to 55% by weight, more preferably 10 to 55% by weight, and most preferably 20 to 50% by weight.
The ultraviolet absorbent polymer used in the invention is contained in the cellulose ester film in an amount of preferably 0.01 to 40% by weight, and more preferably 0.01 to 30% by weight based on the weight of the cellulose ester. When the thickness of the cellulose ester film is not more than 65 xcexcm, the content of the ultraviolet absorbent polymer is more preferably 1 to 10% by weight, and more preferably 1 to 5% by weight based on the weight of the cellulose ester. When the thickness of the cellulose ester film is not less than 70 xcexcm, the content of the ultraviolet absorbent polymer is more preferably 0.5 to 5% by weight, and more preferably 0.5 to 2.5% by weight based on the weight of the cellulose ester. The content of the ultraviolet absorbent polymer used in the invention is not specifically limited, as long as the haze of the cellulose ester film of the invention is 0 to 0.5, but the haze is preferably 0 to 0.2. It is more preferred that the cellulose ester film has a haze of 0 to 0.2 and a transmittance at 380 nm of 0 to 10%.
When the ultraviolet absorbent polymer in the invention is mixed with cellulose ester, another low molecular weight compound, another polymer or inorganic compounds can be mixed. For example, a cellulose ester film comprising the ultraviolet absorbent polymer in the invention and a low molecular weight ultraviolet absorbing compound is one of the preferable embodiments of the invention.
The ultraviolet absorbent polymer in the invention can be used without any limitation as long as it is not a monomer. The weight average molecular weight of the ultraviolet absorbent polymer in the invention is preferably 500 to 1000000, more preferably 1000 to 100000, still more preferably 2000 to 20000, and most preferably 7000 to 15000.
Polymerization methods for obtaining the ultraviolet absorbent polymer in the invention are not specifically limited, but include a radical polymerization, an anion polymerization, and a cation polymerization. Initiators of the radical polymerization include azobisisobutyronitrile (AIBN), azobisisobutyric acid diester derivatives, and benzoyl peroxide.
Solvents used in the polymerization are not specifically limited, but include an aromatic hydrocarbon solvent such as toluene or chlorobenzene, a chlorinated hydrocarbon solvent such as dichloroethane or chloroform, an ether solvent such as tetrahydrofuran or dioxane, an amide solvent such as dimethylformamide, an alcohol solvent such as methyl alcohol, an ester solvent such as ethyl acetate, a ketone solvent such as acetone and water. Solution polymerization in a homogenious phase, precipitation polymerization in which polymerization products precipitate, and emulsion polymerization in a micelle can be carried out by selecting solvents for polymerization.
The ultraviolet absorbent polymer in the invention has an excellent compatibility with cellulose and high molecular weight as compared to the conventional low molecular weight ultraviolet absorbing compounds, and therefore, does not produce bleeding out or crystal precipitation which has been problems during manufacture of a cellulose film or during saponification of the film with an alkali solution, since the repeating unit is a cellulose derivative. Further haze is extremely low, and the ultraviolet absorbent polymer has sufficient resistance to ultraviolet rays, temperature and humidity, and provides a cellulose ester film having an excellent resistance to heat and humidity which does not lower an ultraviolet absorbing property under high humidity and high temperature condition.
The polarizing plate of the invention comprises a polarizing plate protective film, a polarizing element and a second polarizing plate protective film, wherein at least one of the first polarizing plate protective film and the second polarizing plate protective film is the cellulose ester film of the invention.
(Preparation of Polarizing Plate)
The polarizing plate can be prepared according to general methods. There is, for example, a method of treating the cellulose ester film of the invention with an alkali solution, immersing the film in an iodine solution while stretching, and then laminating a polyvinyl alcohol layer onto each surface of the resulting film employing completely saponified polyvinyl alcohol solution. The treatment with an alkali solution is to immerse the cellulose ester film in a strong alkali solution at high temperature in order to improve wettability of the film surface to an aqueous adhesive and improve its adhesiveness.
Next, the cellulose ester in the invention will be explained. The cellulose ester used in the invention is preferably a lower fatty acid ester of cellulose.
The lower fatty acid in the lower fatty acid ester of cellulose is a fatty acid having a carbon atom number of not more than 6. The lower fatty acid ester of cellulose is preferably cellulose acetate, cellulose propionate, or cellulose butyrate.
Besides the above, there can be used a mixture fatty acid ester such as cellulose acetate propionate or cellulose acetate butyrate disclosed in Japanese Patent O.P.I. Publication Nos. 10-45804 and 08-231761, and U.S. Pat. No. 2,319,052.
Cellulose triacetate is especially preferably used as the lower fatty acid ester of cellulose.
The cellulose ester in the invention has a polymerization degree of preferably 250 to 400, and a total substitution degree of preferably 2.3 to 3.0, and more preferably 2.6 to 2.8, in view of film strength. The preferred is cellulose acetate propionate having a total substitution degree of 2.3 to 2.8, an acetyl substitution degree of 1.5 to 2.5 and a propionyl substitution degree of 0.1 to 1.0.
The cellulose triacetate in the invention is a cellulose triacetate synthesized from cotton lint or a cellulose triacetate synthesized from tree pulp, which can be used singly or in combination. If there is any problem in separation of the film from a belt or drum on which the film is formed, the cellulose triacetate synthesized from cotton lint is preferably used in a larger amount, since the triacetate has good separability, and results in higher productive efficiency. When the cellulose triacetate synthesized from tree pulp is mixed, the content of the cellulose triacetate synthesized from cotton lint in the cellulose triacetate mixture is preferably not less than 40 weight %, in view of separability, more preferably not less than 60 weight %, and most preferably 100 weight %.
The polarizing film, which is a main component of the polarizing plate in the invention, is a film transmitting only a light having a wave front of a specific direction. The typical polarizing film is a polyvinyl alcohol polarizing film which is dyed with iodine or two color type dye. The polarizing film is manufactured by making a film from an aqueous polyvinyl alcohol solution, uniaxially stretching the film and dyeing the stretched film or dyeing the film and then uniaxially stretching the dyed film. The resulting film is preferably treated with a boron compound for its durability. The polarizing plate of the invention is formed laminating a transparent polarizing plate protective film in the invention to the surface of the polarizing film.
The manufacturing method of the cellulose ester film of the invention will be explained below.
In the invention dope in which cellulose ester is dissolved is a solution in which cellulose ester is dissolved in a solvent. The dope optionally contains a plasticizer or another additive. The cellulose ester content of the dope is preferably 10 to 30 weight %, and more preferably 18 to 20 weight %.
The solvent used in the invention may be used singly, but is preferably used as a mixture solvent of a good solvent and a poor solvent, in view of productive efficiency. The good solvent content of the mixture solvent is preferably 70 to 95 weight %, and the poor solvent content of the mixture solvent is preferably 5 to 30 weight %. The cellulose ester content of the cellulose ester solution in the invention is preferably 10 to 50 weight %, and more preferably 18 to 20 weight %.
In the invention, a good solvent is defined as a solvent capable of dissolving cellulose esters, and a poor solvent as a solvent which only swells and cannot dissolve cellulose esters. Therefore, whether a solvent is a good solvent or a poor solvent for cellulose esters depends on the acetic acid value of the cellulose ester used. For example, acetone is a good solvent for a cellulose ester with an acetic acid value of 55%, but is a poor solvent for a cellulose ester with an acetic acid value of 60%.
The good solvents in the invention include an organic halogen-containing compound and dioxolane.
Examples of the solvent, which is a good solvent or a poor solvent for cellulose esters depending on the acetic acid value of the cellulose ester used, include acetone, methyl acetate and ethyl acetate.
Examples of the poor solvent used in the invention include methanol, ethanol, n-butanol, and cyclohexane.
In preparation of the dope described above, dissolving a cellulose ester in a solvent is carried out according to conventional processes. The preferable process is a process of mixing a cellulose ester with a poor solvent to swell the ester, and then adding a good solvent to the mixture. In this process, the cellulose ester is preferably dissolved with stirring under increased pressure at from the boiling point at atmospheric pressure of the solvent to a temperature at which the solvent is not boiled, since undissolved matters such as gelled lumps do not produce.
The pressure application is carried out by incorporating to the vessel an inactive gas such as nitrogen with pressure or by increasing a solvent vapor pressure in the vessel by heating. Heating is preferably carried out outside the vessel, and a jacket type vessel is preferable, since heating temperature is easily controlled.
The heating temperature is preferably in the range of from the boiling point of a solvent used to a temperature at which the solvent is not boiled, for example, preferably in the range of 60xc2x0 C. to 70-110xc2x0 C. The pressure applied is determined not to boil the solvent at a given temperature.
After dissolving a cellulose ester in a solvent in a vessel to obtain a dope, the dope is removed from the vessel while cooling, or is removed with a pump and then cooled with a heat exchanger. The resulting cooled dope is used for manufacturing a film. The cooling temperature may be cooled to an ordinary temperature, but is preferably cooled to a temperature of 5 to 10xc2x0 C. below the boiling point of the solvent, since the viscosity of the dope is reduced for casting.
The support used at the casting step is a belt or drum type stainless steel support with a smooth surface. Casting of the solution at the casting step can be carried out in the conventional temperature range of 0xc2x0 C. to a temperature less than the boiling point of the solvent. The dope is cast on the support of preferably 5 to 30xc2x0 C., and more preferably 5 to 15xc2x0 C., since the dope can be gelled to shorten a critical separation time. The critical separation time herein referred to implies time when dope is present on a casting support when the dope is cast on the support at a maximum casting speed capable of continuously forming a transparent film with excellent surface smoothness. The critical separation time is preferably short, in view of productive efficiency.
It is preferred that the surface temperature of the support is 10 to 55xc2x0 C., the dope temperature is 25 to 60xc2x0 C., and the dope temperature is not less than 0xc2x0 C., preferably not less than 5xc2x0 C. higher than the support surface.
The higher the temperature of the support surface or dope is, more preferable, in view of the drying speed. However, too much high temperature thereof results in foaming or deterioration of flatness of the film.
The surface temperature of the support is more preferably 20 to 40xc2x0 C., and the dope temperature is preferably 35 to 45xc2x0 C.
The peeling temperature of the film from the support is preferably 10 to 40xc2x0 C., and more preferably 15 to 00xc2x0 C., since adhesiveness between the support and the film is reduced.
In order to obtain a good flatness of the support, the residual solvent content of the film, when the film is peeled from the support, is preferably 10 to 80%, more preferably 20 to 40%, and most preferably 20 to 30%.
In the invention, the residual solvent content of the film is represented by the following equation:
Residual solvent content=(Weight of film before heating treatmentxe2x88x92weight of film after heating treatment)xc3x97100 (%)/(weight of film after heating treatment)
wherein the heating treatment is to heat the film at 115xc2x0 C. for 1 hour.
Peeling tension, when the film is peeled from the support, is ordinarily 196 to 245 N (20 to 25 kgf)/m. The cellulose ester film of the invention containing a high content of the ultraviolet absorbent polymer, which is thinner than conventional films, is peeled at a peeling tension of preferably from the lowest peeling tension to 167 N (17 kgf)/m, and more preferably from the lowest peeling tension to 137 N (14 kgf)/m, since wrinkles are easy to form.
The cellulose ester film separated from the support is further dried in the drying process to give a residual solvent content in the film of preferably not more than 3 weight %, and more preferably not more than 0.5 weight %.
In the drying process of the film, the film is generally transporting on rollers or in a tenter while drying. The support film for a liquid crystal display member is preferably dried maintaining the film width in a pintenter, which increases dimensional stability of the film. It is especially preferable in view of remarked increased film dimensional stability that the film is dried while holding the film width of a film immediately after the film is separated from the support, which still has a relatively high residual solvent content. The means for drying the film is not specifically limited, but heated air, infrared light, heated rollers or micro waves are generally employed. The heated air is preferably used in view of its convenience. It is preferable that the drying temperature is gradually elevated in separate 3 to 5 stages in the range of from 40 to 140xc2x0 C. It is more preferable in view of film dimensional stability that the drying temperature is gradually elevated in separate 3 to 5 stages in the range of from 80 to 140xc2x0 C.
The cellulose ester film of the invention preferably contains a plasticizer. The plasticizer used in the invention is not limited, but Examples of the plasticizer include a phosphate such as triphenyl phosphate, tricresyl phosphate, cresyldiphenyl phosphate, octyldiphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, or tributyl phosphate, a phthalate such as diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, or di-2-ethylhexyl phthalate, a glycerin ester such as triacetin, tributyrin, and a glycolic acid ester such as butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, or butyl phthalyl butyl glycolate. These plasticizers may be used singly or in combination.
These plasticizers provide a film having an excellent dimensional stability and water resistance.
Combined use of the above-described ultraviolet absorbent polymer and a plasticizer with a melting point of not more than 20xc2x0 C. is preferable in view of processability, prevention of foreign matter trouble or the film surface quality. The plasticizer with a melting point of not more than 20xc2x0 C. is not limited as long as it has a melting point of not more than 20xc2x0 C., and can be selected from the above-described examples. The preferable plasticizers include tricresyl phosphate, cresyldiphenyl phosphate, tributyl phosphate, diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, triacetin, and ethyl phthalyl ethyl glycolate. These plasticizers may be used singly or in combination.
The melting point referred to in the invention is the melting point as described in xe2x80x9cKagaku Daijitenxe2x80x9d, published by Kyoritsu Shuppann Co., Ltd.
The plasticizer content of the cellulose ester film is preferably 1 to 15 weight % based on weight of the cellulose ester, in view of film properties or processability. Further, the plasticizer content of the cellulose ester film for a liquid crystal display material is more preferably 5 to 15 weight %, and especially preferably 7 to 12 weight % based on weight of the cellulose ester, in view of dimensional stability.
Furthermore, the content of the plasticizer with a melting point of not more than 20xc2x0 C. is preferably 1 to 10 weight %, and more preferably 3 to 7 weight % based on weight of the cellulose ester.
Processability herein referred to means processability in slitting or punching a liquid crystal display material. Poor processability provides a jagged slitting surface or produces chips whose adhesion to the film surface results in foreign matter trouble.
The cellulose ester film of the invention is preferably applied to a liquid crystal display material, in view of good dimensional stability or good ultraviolet ray shielding property. The liquid crystal display material is a material used in a liquid crystal display, for example, a polarizing plate, a protective film of a polarizing plate, a phase difference film, a reflection plate, a viewing angle increasing film, an anti-glare film, a non-reflective film, or an antistatic film. The cellulose ester film of the invention is especially preferably applied to a polarizing plate or a protective film of a polarizing plate each requiring an excellent dimensional stability. The thickness of the cellulose ester film of the invention differs depending on its usage, but is preferably 5 to 200 xcexcm, more preferably 10 to 100 xcexcm, and most preferably 20 to 65 xcexcm.
The optical film of the invention optionally contains fine particles as a matting agent. The fine particles used in the invention include inorganic compounds such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, burned kaolin, burned calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. The fine particles are preferably those containing silicon in view of low turbidity, and especially preferably silicon dioxide. The silicon dioxide fine particles are available on the market, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, or TT600 (each produced by Nihon Aerosil Co., Ltd.). The zirconium oxide fine particles are available on the market, for example, Aerosil R976 or R811 (each produced by Nihon Aerosil Co., Ltd.).
Aerosil 200V or Aerosil R972V is especially preferable in that it reduces coefficient of friction and maintains low turbidity of the optical film.
Examples of the polymer fine particles include silicon resins, fluorine-containing resins and acryl resins. Silicon resins are preferable. Silicon resins having a three dimensionally cross-linked structure are especially preferable, which are available on the market, and include for example, Tospar 103, Tospar 105, Tospar 108, Tospar 120, Tospar 145, Tospar 3210 and Tospar 240 (each produced by Toshiba Silicon Co., Ltd.)
Next, the optical compensation film of the invention will be explained. The optical compensation film herein referred to is a film having optical anisotropy used in the liquid crystal display, and generally manufactured by providing on a support an optically anisotropic layer.
The optical compensation film of the invention has an optically anisotropic layer on a support comprised of the cellulose ester film of any one of items 1 through 20 as described previously. The compound used in the optically anisotropic layer is preferably a discotic compound, a biaxial liquid crystalline compound, or a rod-shaped liquid crystalline compound, and more preferably a discotic compound having a nematic phase, a biaxial liquid crystalline compound having a nematic phase, or a rod-shaped liquid crystalline compound having a nematic phase.
Examples of the discotic compound include benzene derivatives, cyclohexane derivatives, polycyclic compounds of azacrown type, polycyclic compounds of phenylacetylene type, triphenylene derivatives, truxene derivatives, phthalocyanine derivatives, anthraquinones derivatives, bullvalene derivatives, bipyranylidene derivatives, and xcex2-diketone complexes. The preferred discotic compounds are discotic liquid crystalline compounds have a structure having the above-described discotic compounds as nucleus in the molecular center and having a straight-chained alkyl group or alkoxy group or a substituted benzoyloxy group in a radiate manner as the molecular side chain. The discotic compounds are not limited thereto as long as they have a negative uniaxiality and can provide a certain orientation.
The biaxial liquid crystalline compound herein referred to is a liquid crystalline compound having two optic axes in the liquid crystal phase. In other words, the biaxial liquid crystalline compound is a compound satisfying n1 less than n2 less than n3, wherein n1, n2, and n3 represent a refractive index in three axis directions. Examples of the biaxial liquid crystalline compound include liquid crystalline compounds described in for example, xe2x80x9cHandbook of Liquid Crystals Chapter XV Biaxial Nematic Liquid Crystalsxe2x80x9d. However, the biaxial liquid crystalline compound is not limited to those described above, as long as it is a compound capable of providing a certain orientation in which refractive index in one direction is different from refractive index in another direction.
The rod-shaped liquid crystalline compound is the most general liquid crystalline compound, and a compound whose molecule is regarded as being rod-shaped. The rod-shaped compound is a compound in which when xe2x80x9caxe2x80x9d is a major axis and xe2x80x9cbxe2x80x9d is a minor axis, a/b is sufficiently large. a/b is preferably not less than 2, and more preferably not less than 3. However, the rod-shaped liquid crystalline compound is not limited to those described above, as long as it is a positive uniaxial compound capable of providing a certain orientation.
These liquid crystalline compounds are used singly or as a mixture of two or more kinds. These compounds may be low molecular or high molecular compounds. Orientation of these compounds is fixed without losing the orientation form in the liquid crystal phase as follows. These compounds are mixed with polymers, these compounds are elevated to temperature developing the liquid crystal phase, and then cooled maintaining the orientation form, or a composition containing a liquid crystalline compound in which a polymerizable group is incorporated and initiator is elevated to temperature developing the liquid crystal phase, followed by polymerization.
The materials for a protective film include polymers such as polymethyl methacrylate, acrylic acid-methacrylic acid copolymer, styrene-maleimide copolymer, polyvinyl alcohol, poly(N-methylolacrylamide), styrene-vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, and polycarbonate, and compounds such as silane coupling agents. The materials for a protective film include a multi-layered film (LB film) of xcfx89-tricosanoic acid, dioctadecylmethyl-ammonium chloride or methyl stearate, which is formed according to a Langmuir-Projet method.
The light source for polymerization is preferably an electron beam, ultraviolet light, visible light, or infrared light (heat ray), and more preferably ultraviolet light. Radical polymerization employing a photopolymerization initiator or cation polymerization, which is carried out employing ultraviolet light, is preferable in view of polymerization speed and productivity. The light source for radical polymerization is preferably a low pressure mercury lamp, a high pressure discharging lamp or a short arc discharging lamp, and more preferably a high pressure discharging lamp.
The optical compensation film of the invention is a film for compensating a viewing angle of a liquid crystal display, preferably a film in which a director on one side of the film is different from that on the other side, and more preferably a film in which the hybrid orientation gradually varies in the film thickness direction.
In order to obtain the hybrid orientation in the invention, a liquid crystalline material is provided between two different boundaries, or electric field or magnetic field is applied. One embodiment employs one substrate and atmospheric boundary, in which one side of a liquid crystalline layer has the substrate, the other side of the liquid crystalline layer facing atmospheric air. It is preferred that the liquid crystalline layer is coated on the substrate, with one side of the liquid crystalline layer facing atmospheric air.
An oriented plate preferably used in the invention controls an orientation direction of a liquid crystalline compound in an optically anisotropic layer. The oriented plate has for example, a rubbing layer containing an organic compound (preferably a polymer), an inorganic compound oblique evaporation layer, a layer having a microgruoub, or a multi-layered film (LB film) of xcfx89-tricosanoic acid, dioctadecylmethylammonium chloride or methyl stearate, which is formed according to a Langmuir-Projet method. Further, an oriented plate can be used, which has a layer capable of producing orientation by application of an electric or magnetic field or by light irradiation.
The optical compensation film of the invention can be obtained by coating on the above-described oriented plate the above-described liquid crystalline compound, orienting uniformly the compound and then fixing the oriented compound. The coating is carried out employing a solution in which the liquid crystalline compound is dissolved in a solvent or the liquid crystalline compound to have been heat fused, and preferably is carried out employing the solution.
The above-described solution is coated on the above-described oriented plate. The coating methods include an evaporation method, a spin coating method, a dip coating method, and an extrusion method. After coating, the solvent is removed and dried to form a layer with uniform film thickness on the plate. The coated layer is dried at room temperature, on a hot plate, in a drying chamber, or blowing a warm or hot air.
In order to orient the liquid crystalline compound, heat treatment is preferably carried out, and the heat treatment is carried out at temperature of not less than a liquid crystal transition point of the liquid crystalline compound. That is, the liquid crystalline compound is oriented in the liquid crystal state, or is oriented by elevating to temperature not less than a temperature range developing a liquid crystal state to form an isotropic state, and then cooling to temperature developing a liquid crystal state. Temperature in the heat treatment is ordinarily 0 to 200xc2x0 C., and preferably 20 to 150xc2x0 C.
In the invention, electric field or magnetic field may be used in the above heat treatment in order to orient the liquid crystalline compound. The above orientation is fixed by cooling or by polymerization due to light or heat application without losing the orientation to obtain the optical compensation film of the invention.
Application of one or more of the optical compensation film of the invention to a liquid crystal display can develop excellent optical compensation effects. One embodiment of the liquid crystal display of the invention is a liquid crystal display comprising a first polarizing plate, a second polarizing plate, and a liquid crystal cell provided between the first and second polarizing plates, the first polarizing plate being arranged on the viewer side of the display. The first polarizing plate has a first film, a second film and a first polarizing film between the first and second films so that the second film is provided on the first polarizing film on the liquid crystal cell side. The second polarizing plate has a third film, a fourth film and a second polarizing film between the third and fourth films so that the third film is provided on the second polarizing film on the liquid crystal cell side. Further, at least one of the first, second, third and fourth films is the cellulose ester film of the invention. The first film is preferably the cellulose ester film of the invention.
Next, synthetic examples of the ultraviolet absorbent polymer will be explained. However, the invention is not limited thereto (synthetic examples 1 through 9).